Process of purifying tetra alkyl lead



Patented Oct. 2, 1934 u irs Alfred EfP armelee, Carneys loinflli. .I assi 'gn or: v Q

i to E. I. du Pont de Nemours &Gompany,-;W ilmingto'm D eL, a corporation of Delaware p c h arcli. 2 .5 931; Serial No. 5.2 .14; 21,231;

No Draw n 8 Claims. (Cl. 260-11) This invention relates to the process of producing tetra alkyl lead and more particularly to the process of removing sludge in such processes.

When tetra alkyl lead is recovered by steam distillation from the reaction mass in which it is formed, there is carried over a very appreciable amount of finely divided metallic lead and also organic derivatives of lead which are solids. These solid materials remain suspended in the tetra alkyl lead and are so fine that they are not readily removed by any common means of filtration. The ordinary clarifying agents such as diatomaceous earth and charcoals may not be used with ease or safety for clarifying because the tetra alkyl lead which is absorbed upon their surface will catch fire spontaneously on exposure to air.

An object of my invention is to overcome the difficulties heretofore experienced in the manufacture of tetra alkyl lead, and particularly tetra ethyl lead. A further object of my invention is the removal of suspended matter in tetra alkyl lead processes. Other and further objects will appear hereinafter.

These objects are accomplished by the following invention in which I have found that the solid particles which are suspended in tetra ethyl lead may be coagulated and caused to separate by floating to the interfacial layer if the tetra ethyl lead is washed with relatively dilute solutions of one of several inorganic compounds and organic compounds, or mixtures of such compounds, Those compounds which possess strong detergent and wetting properties have been found especially efi'icacious for my purpose. Such compounds comprise trisodium phosphate, borax, sodium car- 'bonate, sodium sulfite, sodium metasilicate, so-

dium bisulfite and commercial wetting agents known as Nekal A, which is the sodium salt of the condensation product of naphthalene sulfonic acids and isopropyl alcohol. Other similar condensation products may also be used.

With the View of more clearly disclosing my invention the following illustrative example of one specific embodiment thereof is given.

Ewample 30,000 to 40,000 pounds of crude tetra ethyl lead are placed in a suitable washer which is provided with an agitator. 500 gallons of water in which have been dissolved 10 to 20 pounds of trisodium phosphate are then added and the mixture is agitated for 10 minutes to 1 hours. The agitation is then stopped and the charge allowed to settle for one or more hours. When the settling period has been completed it will be found that the solids which were suspended in the tetra ethyl lead have been wetted by the water solution of trisodium phosphate and will have collected at the interfacial layer between the two liquids. This makes it possible to draw off, from the bottom, the tetra ethyl lead in a purified condition and free from suspended sludges.

While my invention is illustrated specifically as applied to the manufacture of tetra ethyl lead, it will be understood that it may be applied in a similar manner in the manufacture of any of the tetra alkyl lead compounds, such as tetra methyl lead, tetra butyl lead, tetra propyl lead, etc.

The term sludge as used herein is to be understood as applied to the finely divided lead, etc., in suspension in the tetra ethyl lead, or like compounds.

As many apparently widely difierent embodiments of this invention may be made without departing from the spirit thereof, it is to be under-' stood that I do not limit myself to the foregoing examples or descriptions except as indicated in the following patent claims.

I claim:

1. The process of removing suspended matter from tetra alkyl lead which comprises agitating the tetra alkyl lead with an aqueous solution of a compound having pronounced wetting and detergent properties, permitting the tetra alkyl lead to separate from the aqueous solution, and then drawing off the purified tetra alkyl lead.

2. The process of removing suspended matter from tetra alkyl lead which comprises agitating the tetra alkyl lead with an aqueous solution of a compound of the group consisting of borax, sodium carbonate, trisodium phosphate, sodium sulfite, sodium bisulfite, and the sodium salt of the condensation product of naphthalene sulfonic acid and isopropyl alcohol, permitting the tetra alkyl lead to separate from the aqueous solution, and then drawing off the purified tetra alkyl lead.

3. The process of removing suspended matter from tetra alkyl lead which comprises agitating the tetra alkyl lead with an aqueous solution of trisodium phosphate, permitting the tetra alkyl lead to separate from the aqueous solution, and then drawing off the purified tetra alkyl lead.

4. In the process of producing tetra alkyl lead, the step which comprises distilling off the tetra alkyl lead from a reaction mass containing the same, treating the distilled tetra alkyl lead with an aqueous solution of a compound having pronounced wetting and detergent properties, permitting the tetra alkyl lead to separate from the from tetra ethyl lead which comprises agitatingv the tetra ethyl lead with an aqueous solution of .a-

compound of the group consisting of borax,

sodium carbonate, trisodium phosphate, sodium sulfite, sodium bisulfite, and the sodium salt of the condensation product of naphthalene sulfonic acid and isopropyl alcohol, permittingthe tetra ethyl lead to separate from the aqueous solution, and then drawing off the purified tetra ethyl lead.

'7. The process of removing suspended matter from tetra ethyl lead which comprises agitating the tetra ethyl lead with an aqueous solution of trisodium phosphate, permitting the tetra ethyl lead to separate from the aqueous solution, and

' then drawing ofi the purified tetra ethyl lead.

v 1 8. In the process of producing tetra ethyl lead, the step which comprises distilling off the tetra ethyl lead from a reaction mass containing the saine, treating the distilled tetra ethyl lead with an aqueous solution of a compound having pronounced wetting and detergent properties, permitting the tetra ethyl lead to separate from the aqueous solution, and then drawing oil the purified tetraethyl lead; ALFRED E. PARMELEE. 

